An Innovative Positive Pressure Walk-in Tunnel for Minimizing Insect Infestation and Pesticide Use for Growing Fresh Herbs

Infestation with insects disqualifies fresh spice herbs for local and export markets, severely affecting revenue and the grower’s reputation. An innovative positive pressure walk-in tunnel, in which air is drawn and filtered via insect screens into an enclosed, pressurized growing structure was designed and tested as a solution for mitigating crop infestation. In four field trials between 2019 and 2024 with sweet basil ( Ocimum basilicum ), the efficacy of the positive pressure tunnel was tested and compared with the current commercially used passive, pesticide-sprayed tunnel. Insect counts were reduced by 81%. Yields were 55% higher than in the passive control, and basil downy mildew (BDM), caused by Peronospora belbahrii , was inhibited in two of three trials in the pressurized system without pesticides. Over the 4-year study, chemical pesticide use was reduced by 88% and the number of basil harvests increased by 33%. An economic viability for sweet basil calculated the positive pressure tunnel to be $22,000 USD/hectare more profitable than the currently used passive tunnels. The research verified that the positive pressure tunnel was effective in reducing insect penetration and minimizing pesticide applications. Growers incorporating this innovative apparatus are expected to produce crops with reduced pesticide exposure or pesticide-free, appealing to customers’ desire for high-quality produce.